Electrically controlled interior lights are an accessory found on automobiles. In a typical arrangement, the lights are mounted in the ceiling of the automobile, on the side panel of the door, or in various other interior places where lighting is beneficial. The interior lights incorporated in automobiles of the present and past are controlled by electro-mechanical switches. For instance, most automobiles provide circuitry to automatically turn on an interior light of the automobile when the door of the automobile is opened and to automatically turn off the interior light when the automobile door is closed. Additionally, most vehicles are equipped with a switch which allows the operator of the vehicle to manually turn the interior light between an "on" and an "off" position.
However, there are problems associated with the interior lighting control systems of the prior art. Often the operator of the automobile opens the door, sits down in the automobile, and then shuts the car door. When the door is closed, the interior light automatically, and virtually instantaneously, shuts off. The operator of the vehicle is thereby surrounded by darkness. Quite often, the operator of the vehicle needs the illumination of the interior light to perform some function, such as finding the keys of the car, before driving the car. While most automobiles are equipped with switches which allow the operator to manually turn the interior light on, such a switch requires the operator to fumble around in the darkness in an effort to find and activate the switch.
Another problem associated with the prior art concerns an inadvertent mistake by the driver in deactivating the interior light after it has been activated with the manual switch. The problem arises when a vehicle operator turns on the interior light with the manual switch, forgets to turn off the interior light after using it, and then turns off the engine and leaves the vehicle. In such a scenario, the interior light remains on, thus depleting the car battery voltage level.
Yet another problem associated with the prior art interior lighting systems concerns their virtually instantaneous on or off condition. That is, when circuitry is activated to turn on or off the interior light of the automobile, the light level of the interior light reaches a maximum or minimum level almost instantaneously. An instantaneous on or off interior lighting system prevents the operator's eyes from adjusting gradually to the new lighting condition. While the instantaneous switching may only cause the operator discomfort under some circumstances, the instantaneous switching may have a temporary blinding effect upon the operator which could prove hazardous if it occurs while the operator is driving the vehicle.
To solve these and other problems, the inventor herein has succeeded in developing an improved interior lighting system for automobiles. The invention includes a manual switch which allows the operator of the automobile to switch the interior lights between an on or an off position. The invention provides circuitry to automatically turn off the interior light after approximately five minutes have lapsed from the time that the interior light was activated with the manual switch, if the automobile ignition switch is in the "off" position. The invention provides circuitry to prevent the automatic turn off when the ignition switch is in the "on" position. This prevents the annoyance of having to turn the lights back on after 5 minutes have lapsed. For example, this situation might arise when a passenger is reading a map while the automobile is being driven.
The invention also provides a door switch which automatically turns on the interior light of the automobile when a door of the automobile is opened, and incorporates circuitry which automatically generates an electrical signal to turn off the interior light a preselected time, such as thirty seconds, after the door of the automobile is closed. This invention also includes a circuit which causes the thirty second delay to be cancelled when the ignition switch is turned on.
Finally, this invention provides a delay circuit which is electrically connected between the manual and the door switch and the interior light. Any electrical signal generated by the door switch or the manual switch to turn on or off the interior light of the automobile are received by the delay circuit. The delay circuit causes the light level of the interior light to rise transiently to a maximum level in response to an electrical signal to turn on the interior light, and causes the light level of the interior light to decay transiently to a minimum level in response to an electrical signal to turn off the interior light.
The following sets forth objects of one or more of the claims for the invention. It is an object to provide a lighting system with a delay which causes the interior light of an automobile to rise slowly to a maximum when the light is turned on and to decay slowly when the light is turned off. Another object is to provide a lighting system which gradually switches between an on and an off illumination level for an interior light to prevent operator discomfort and momentary blinding.
It is further an object to provide means to generate electrical signals for turning the interior light of the automobile on and off. It is an object to have a manual generating means that allows the operator of the automobile to a manually activate a momentary switch between an on and off position, and further, to have a shut-off means that automatically shuts off the interior light after a period of time elapses from the light being activated manually so that battery rundown is prevented. It is also an object to provide circuitry to override the automatic shut off circuitry when the ignition is turned on.
Another object is to provide a door switch means which automatically turns on the interior light of the automobile when the door of the automobile is opened, and which allows a predetermined time to lapse after the door is closed before the interior light is automatically turned off. Moreover, an object is to provide an ignition means to override the predetermined time delay when the ignition is turned on.